In image forming apparatuses such as copying machines and printers, the processing speed constitutes an important factor that determines the performance of the apparatus. In this regard, developments have been made to meet the demand for faster processing speed. For example, the print processing capability of “high-speed machines” has rapidly increased to 100 to 120 sheets/minute (A4-size paper, lateral feed) as compared with 50 to 70 sheets/minute (A4-size paper, lateral feed) only a few years ago. Under these circumstances, the applicable areas of such high-speed machines, from the standpoint of processing speed, now include near-printing, outside the domain of the image forming apparatus. It is therefore necessary in such high-speed image forming apparatuses to stably transport printing paper at high speed while ensuring good print quality.
In conventional image forming apparatuses, the transfer belt system has been pervasive as the system suited for high-speed processing. In image forming apparatuses adapting the transfer belt system, a printing paper electrostatically attracted to a surface of a transfer belt is transported so that a toner image formed on a surface of a photoreceptor is transferred onto the printing paper, as described in Patent Publication 1. The printing paper on the transfer belt is then sent to a fixing device, where the toner image on the printing paper is fixed thereon.